Small spruce bark beetle - Polygraphus poligraphus L.From: Kolk A., Starzyk J. R., 1996: The Atlas of Forest Insect Pests Occurrence: Europe, Asia Minor and Siberia. Host plants: The Norway spruce, occasionally Scots pine, fir, eastern white pine and larch. Morphology: Beetles are 1.8-3.5 mm long, cylindrical, elongated, brown or dark brown. Elytrae are dull, with unclear rows of punctures, and covered with brownish scales. Eyes are divided into two, triangle-shaped parts, thus the beetle looks like having four eyes. The egg is transparent, white, 0.6 mm long. The larva is legless. The mature larva reaches 4-5 mm in length. The pupa is first white, then dark brown. Biology: Beetles or larvae overwinter under the bark in galleries. Adults of the first generation fly in late-April or May. Adults of the second generation initiate flying in July or in the first half of August. Occasionally this species may have a sister generation, thus all developmental stages occur during a season. The male prepare the nuptial chamber and attracts 1-6 females. They tunnel egg galleries of 2-6 cm in length and 1.2 mm in width, where lay eggs in niches. Legless larvae chew irregular, curved galleries. In the part of stems with the thin bark they pupate in the sapwood, and in the part of stems with thick bark pupation occurs in the bark. Young adults emerge 8-12 days later and have maturation feeding in and around larval galleries. Damage: P. poligraphus is one of the most serious physiological pest of spruce. It often occurs together with Ips typographus and Pityogenes chalcographus. This species attacks mainly young weakened trees up to 30 cm dbh. It infests the whole stem and branches of standing trees and upper and middle parts of the freshly cut trees. Preventive measures: Cutting and removal of weakened trees and woody debris. Storage of timber in sunny places is recommended. Control:
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Forest Pests: Insects, Diseases & Other Damage Agents |
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